Automatic Detection and Adjustment of a Pressure Pod Diaphragm

ABSTRACT

A system for controlling the position of a diaphragm in a diaphragm-containing pressure pod, is provided. The system can include a peristaltic pump, a pressure pod having a flow-through fluid side and a gas side that are separated by a diaphragm, and a pressure sensor operatively connected to the gas side. The pressure sensor is configured to sense pulses of pressure resulting from movement of the diaphragm and caused by the action of the peristaltic pump. A gas source and a valve can be in fluid communication with the gas side of the pressure pod and can be configured to provide gas to, or vent gas from, the gas side. A controller receives pressure signals from the pressure sensor and controls the valve in response, and in so doing, controls the position of the diaphragm. Methods for positioning the diaphragm are also included.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/022,932, filed Mar. 18, 2016, now U.S. Pat. No. 9,833,554 B2, issuedon Dec. 5, 2017, which in-turn is a 371 filing from InternationalApplication No. PCT/US2014/067200, filed Nov. 25, 2014, which is acontinuation of U.S. patent application Ser. No. 14/139,061, filed Dec.23, 2013, now U.S. Pat. No. 8,960,010 B1, issued on Feb. 24, 2015, allof which are incorporated herein by reference in their entities.

FIELD OF THE INVENTION

The present invention relates to a method and system for the automaticdetection and adjustment of a pressure pod diaphragm used in an airlessbloodline system.

BACKGROUND OF THE INVENTION

Airless bloodline systems have been implemented to include arterial andvenous pressure monitor features known as “pressure pods.” These podsconsist of a molded plastic feature integrated into the bloodline systemto transmit pressure information from a blood side of the pod, across athin diaphragm, to a measurement feature of the machine. Under certainoperating conditions, for example, caused by operator errors, leaks, ordamaged tubing, there is a possibility that the diaphragm can becomepressed against the rigid inner surface or shell wall of the pressurepod, as shown in FIG. 2B. When this happens, the pressure monitoringfeature of the dialysis machine is no longer able to respond to pressureincreases and records a constant incorrect pressure reading. When thepressure pod diaphragm gets pushed against the pressure pod innersurface, the orientation prevents increased pressure from beingmonitored. A user must visually detect this condition and manuallyadjust the diaphragm.

SUMMARY OF THE INVENTION

The present teachings relate to a system and method for detecting andautomatically adjusting the position of a pressure pod diaphragm withinan airless bloodline system. The method uses an algorithm to detect theposition of the diaphragm and automatically uses pressure adjustments tomove the diaphragm away from the shell wall. The system can include anarterial pressure pod located at an inlet of an arterial blood pumpmodule, and a venous pressure pod located on the venous (outlet) side ofa dialyzer. A pressure port can be connected to a level detector moduleof the hemodialysis system. The diaphragm, when properly positionedwithin the pressure pod, is adequately flexible to transmit bloodpressure information across the entire pressure monitoring range.

An existing machine drip chamber level adjustment feature containedwithin an arterial blood pump and level detector module can be appliedto manipulate the position of the pressure pod diaphragm. Theconventional use of these level controls is for manual operatoradjustment of the liquid/air level in the arterial and venous dripchambers of a conventional bloodline. In accordance with the presentteachings, however, additional hardware and software is implemented toutilize these module level controls as an automatic machine feature. Inthe case of the arterial pressure pod, the machine software monitors thearterial pressure. If the periodic arterial pressure pulses caused bythe blood pump rotation are not detected, or if other predictablepressure signals or fluctuations caused by other factors are notdetected, the software algorithm issues a command to activate the levelcontrol for the arterial pressure pod, at least momentarily, to push,pull, or otherwise force the diaphragm away from the shell wall. For thevenous pressure pod, the machine software monitors the venous pressure.If the periodic venous pressure pulses caused by the blood pump rotationare not detected, or if other predictable pressure signals orfluctuations caused by other factors are not detected, the softwarealgorithm issues a command to activate the level control for the venouspressure pod, at least momentarily, to push, pull, or otherwise forcethe diaphragm away from the shell wall. For either pressure pod, thesystem can automatically, at least momentarily, turn on a level downpump or open a level up valve and automatically adjust the diaphragmaway from the shell wall. For either pressure pod, additionaladjustments can also be provided to force the diaphragm away from theshell wall or to force the diaphragm further away from the shell wall.The algorithm can implement a pulse width modulated control signal toprecisely meter an amount of pressurized gas to move the diaphragm, orprecisely meter an amount of gas to be vented from the pressure pod.

The present teachings free a user from the task of manually positioningthe diaphragm and provide more accurate and timely level adjustment thancan be achieved by manual means.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more fully understood with reference to theaccompanying drawings. The drawings are intended to illustrate, notlimit, the present teachings.

FIG. 1A is a perspective view in partial cross-section showing aflow-through pressure pod, with the diaphragm removed, that can be usedin accordance with the present teachings.

FIG. 1B is a cross-sectional side view of the pressure pod shown in FIG.1A, but wherein the diaphragm is shown and is positioned in an extremeupper position against the upper inner sidewall of the pressure pod.

FIG. 2 is a schematic, cross-sectional view of a pressure pod includinga diaphragm shown in a mid-body position between a lower half and anupper half of a diaphragm chamber.

FIG. 3 is a schematic illustration of a pressure pod diaphragm controlsystem in the form a block diagram, showing a system in accordance withthe present teachings and comprising both an arterial side pressure podand a venous side pressure pod.

FIG. 4 is a process flow diagram showing the algorithm involved withautomatically controlling the position of a pressure pod diaphragm, inaccordance with various embodiments of the present teachings.

FIGS. 5A-5C are three graphs showing waveforms representing pressuresignals generated by an arterial side pressure pod, over time, includinga graph that corresponds to pressure measurements taken under normal,proper operating conditions (FIG. 5A), a graph that corresponds topressure measurements taken under conditions wherein the pressure poddiaphragm is stuck in a first, extreme, over-pressurized position (FIG.5B), and a graph that corresponds to pressure measurements taken underconditions wherein the pressure pod diaphragm is stuck in a second,extreme, under-pressurized position (FIG. 5C).

DETAILED DESCRIPTION OF THE INVENTION

According to one or more embodiments of the present invention, a systemis provided for controlling the position of a diaphragm in adiaphragm-containing pressure pod. The system can comprise a fluid pump,a pressure pod, a pressure sensor operatively connected to the pressurepod, and a controller configured to receive a pressure signal generatedby the pressure sensor and to control a gas pressure inside the pressurepod based on the pressure signal received. Controlling the gas pressureinside the pressure pod can be used to position the diaphragm within thepressure pod so that can it can accurately generate pressuremeasurements.

The pressure pod can comprise any of a variety of pressure pods used tomeasure the pressure of a fluid flowing through the pod. The pressurepod can comprise of an interior, defining a flow-through fluid side anda gas side. The flow-through fluid side and the gas side can beseparated from one another by the diaphragm. Exemplary pressure podsthat can be used in accordance with the present teachings include thoseshown and described, for example, in U.S. Pat. No. 8,210,049 B2, U.S.Pat. No. 8,092,414 B2, U.S. Pat. No. 6,526,357 B1, U.S. Pat. No.3,863,504, and European Patent Application Publication No. 0 30 891 A1,each of which is incorporated herein in its entirety, by reference.

A fluid conduit can be provided in fluid communication with theflow-through fluid side of the pressure pod. The fluid conduit can beoperatively positioned with respect the fluid pump such that the pumpcan move fluid through the conduit and force fluid through theflow-through fluid side of the pressure pod. In some cases, the fluidpump can be arranged to push fluid through the fluid conduit and throughthe pressure pod. In other embodiments, the fluid pump can be arrangedto pull fluid through the conduit and through the pressure pod. Thefluid pump can comprise a peristaltic pump and the fluid conduit can bepositioned so as to be acted upon by a rotor of the peristaltic pump,for example, in a raceway or semi-circular track.

The pressure sensor can be operatively connected to the gas side of thepressure pod and can be configured for sensing pressure resulting frommovement of the diaphragm. To maintain the diaphragm in a mid-section ormid-body position in the interior of the pressure pod, for example, toaccurately sense increases and decreases in the pressure of fluidflowing through the pressure pod, it may become necessary to vent gasfrom the gas side of the pressure pod, or to pressurize the gas side ofthe pressure pod, or to do both. A gas source can be provided in fluidcommunication with the gas side of the pressure pod and can comprise avalve and/or regulator configured to provide a fluid communicationbetween the gas side and the gas source. The valve and/or regulator canalso be configured to interrupt communication between the gas side andthe gas source, for example, to prevent the gas source from pressurizingor further pressurizing the gas side. The valve and/or regulator can beconfigured to take on an open or venting position to thereby form afluid communication between the gas side and a vent port, for example, avent port leading to an ambient atmosphere. In the open or ventingposition, the valve and/or regulator can enable pressurized gas toescape from the gas side of the pressure pod, for example, to releasepressure from the gas side, which pressure may have caused the diaphragmto have moved too far towards the flow-through fluid side and away froma more mid-body position. As mentioned before, the mid-body position isoften a preferred diaphragm position for sensing pressure fluctuations.Herein, while many references are made to a valve or to valves, it is tobe understood that a regulator is considered herein to constitute onetype of valve that can be used.

In one or more embodiments of the present teachings, the fluid pump cancomprise a peristaltic pump and the pressure sensor can be configuredfor sensing pulses of pressure caused by the peristaltic pump movingfluid through flow-through fluid side of the pressure pod. Thecontroller can be configured to compare a pressure signal received fromthe pressure sensor, to a predetermined pressure signal, for example, toa predetermined pressure signal that corresponds to a signal generatedduring normal operation of the pressure pod, under normal operatingpressures, and where the diaphragm is properly or optimally positioned.In some cases, the controller can be configured to determine whether thepressure signal received is within an acceptable degree of variancerelative to the predetermined pressure signal. A standard deviation canbe calculated based on the difference between the pressure signalreceived from the pressure sensor and the predetermined pressure signal.The standard deviation can be compared to threshold values, for example,compared to maximum and minimum threshold values, to determine whetherthe pressure pod is working properly and/or whether the diaphragm isproperly positioned within the pressure pod.

The pressure signal received from the pressure sensor can be compared toa plurality of predetermined signals. At least one of the plurality ofpredetermined signals can correspond to a signal generated by operationof the pressure pod when the diaphragm is in a first extreme position.The first extreme position can be, for example, a position where the gasside of the pressure pod is minimized, and the flow-through fluid sideof the pressure pod is maximized. Such a position of the diaphragm wouldbe undesirable and would prevent the pressure pod from generatingincreased pressure pulses because the diaphragm would already be in afully extended or fully pressurized position. In such a position, thediaphragm would not be able to move further in response to increased gaspressure and thus would not be capable of delivering a pressure pulse tothe pressure sensor. The pressure signal received from the pressuresensor can be compared to a predetermined signal generated when thediaphragm was in a second extreme position wherein the flow-throughfluid side of the pressure pod is minimized, and the gas side of thepressure pod is maximized. In the second extreme position, the diaphragmwould have been fully extended toward the flow-through fluid side suchthat any further decreases in pressure would not be able to be detected.

If the controller determines that the pressure signal received from thepressure sensor is similar to the predetermined signals whereby thediaphragm had been in one of the extreme positions, then the controllercan actuate the gas source and valve to pressurize or vent the gas sideof the pressure pod. In so doing, the diaphragm can be moved to a moremid-body position within the pressure pod. Logic circuitry known tothose skilled in the art can be provided to enable the controller tocontrol the valve, gas source, or both, to either vent the gas from thegas side, pressurize the gas side with the gas source, or both, asappropriate. In so doing, the position of the diaphragm can be adjusted.If the pressure signal received from the pressure sensor is determinedto be similar to a predetermined pressure signal corresponding to normaloperation of the pressure pod, then the controller can maintain thevalve, and gas source, in the then-current states such that noadjustments are made or deemed necessary.

The pressure signal can be periodically, intermittently, randomly, orcontinuously sent to and received by the controller. Upon making anadjustment to the gas pressure in the gas side, the controller can pauseor wait before comparing the resulting pressure to the predeterminedsignals. In some cases, the controller can immediately compare the newpressure signal resulting from an adjustment, to one or morepredetermined signals.

The pressure signal generated by the pressure sensor can be more thanone second in length, for example, along a time axis. The signal can begenerated over a period of time, for example, over a period of twoseconds, three seconds, five seconds, seven seconds, ten seconds, orlonger. The length of the pressure signal can be equal to the amount oftime it takes for the pump to produce one, two, three, or more pulses ofpressure. In some cases, a peristaltic pump is used and the signal to becompared is generated over the amount of time needed for the pump togenerate two, three, or four pressure pulses.

The gas source can comprise pressurized gas under a pressure of greaterthan 1 atmosphere, for example, under a pressure of 1.5 atmospheres,under a pressure of 2 atmospheres, under a pressure of 3 atmospheres, ormore. The gas source can comprise gas under pressure of from 1.1atmospheres to 100 atmospheres, of from 1.1 atmospheres to 10atmospheres, of from 1.1 atmospheres to 5 atmospheres, or of from 1.5atmospheres to 3.0 atmospheres. In some cases, the gas source cancomprise a gas compressor and a tank for holding pressurized gas, forexample, at a pressure of from about 5 psig to about 150 psig, of fromabout 10 psig to about 100 psig, or of from about 15 psig to about 50psig. The gas source can comprise pressurized air, carbon dioxide,nitrogen, another inert gas, or the like. The gas source can comprise agas pump or an inflator.

The valve can be configured to be a part of the gas source, or simply influid communication with the gas source. In some cases, the valve cancomprise two valves, one for controlling a fluid communication betweenthe gas side and the gas source, and one used for controlling a vent tovent gas pressure from the gas side of the pressure pod. In some cases,the valve, or each valve, can comprise a T-valve, a pin valve, athreaded closure valve, a numerically-operated valve, ahydraulically-operated valve, or the like. The valve can comprise amulti-wave valve, for example, a valve that can assume a closed state, aventing state whereby gas pressure in the gas side of the pressure podcan be vented, and a gas inlet state whereby pressurized gas from thegas source can be in fluid communication with the gas side of thepressure pod. Operation of the valve, or of each valve, can becontrolled by the controller, by using, for example, control logic,servo-motors, stepper motors, pneumatics, hydraulics, combinationsthereof, and the like.

Any one of a variety of valves can be used as part of, or in connectionwith the gas source. The valve can be selected from any of the followingtypes: a ball valve; a butterfly valve; a check valve; a gate valve; aneedle valve; a quarter-turn valve; a flow control valve; a gas pressureregulator; a plunger valve; a pressure regulator; a pressure reducingvalve; a pressure sustaining valve; a back-pressure regulator; a saddlevalve; a safety valve; a relief valve; a solenoid valve; and a stopcock.The valve can be controlled by any of a variety of systems and devices.The valve or valves can be controlled by actuators, for example,attached to a valve stem. The actuators can be electromechanicalactuators, including, for example, an electric motor or solenoid,pneumatic actuators that are controlled by air pressure, or hydraulicactuators that are controlled by the pressure of a liquid such as oil orwater. Actuators can be used for automatic control, remote control, or acombination thereof. Pneumatic actuators and hydraulic actuators can beused that work based on pressurized air or liquid lines. A pilot valvecan be used to control one or more other valves. Pilot valves inactuator lines can be used to control the supply of air or liquid goingto actuators. In some valve designs, the pressure of the gas flow itselfor a pressure difference of the gas flow between ports can be used toautomatically control flow through the valve.

The pressure sensor can be a modular unit, a permanent unit, areplaceable unit, or the like. The pressure sensor, being in fluidcommunication with the gas side of the pressure pod, does not come intocontact with the fluid flowing through pressure pod on the flow-throughfluid side. Therefore, at no time is the pressure sensor contaminated bythe fluid and thus the pressure sensor can be configured as a re-usablecomponent of the system.

The pressure sensor can comprise an inlet port into which a pressureline, such as pressure tubing or air tubing, can be connected to form afluid communication between the gas side of the pressure pod and thepressure sensor. The gas side of the pressure pod can have a port. Thegas side port and the inlet port for the pressure sensor can have thesame inner diameter, the same outer diameter, or both, for example, sothat a pressure tube of fixed outer diameter can be connected to boththe gas side of the pressure pod and to the inlet port of the pressuresensor.

The pressure sensor can comprise one or more of the pressure sensorsdescribed, for example, in any of U.S. Pat. No. 8,210,049 B2, U.S. Pat.No. 8,092,414 B2, U.S. Pat. No. 6,526,357 B1, U.S. Pat. No. 3,863,504,and European Patent Application Publication No. 0 30 891 A1, each ofwhich is incorporated herein in its entirety, by reference.

With the reference to the drawing figures, FIG. 1A is a perspective viewin partial cross-section showing a flow-through pressure pod, with thediaphragm removed, that can be used in accordance with the presentteachings. FIG. 1B shows a cross-sectional side view of the pressure podshown in FIG. 1A, but wherein the diaphragm is shown and is positionedin an extreme upper position against the upper inner sidewall of thepressure pod. As can be seen in FIGS. 1A and 1B, pressure pod 100comprises an upper shell 102, a lower shell 104, and a diaphragm 106.Lower shell 104 can be configured, as shown, to define a flow-throughtube 108 that includes an inlet port 110 and an outlet port 112. Lowershell 104 also defines a bottom half 114 of a diaphragm chamber 116.Bottom half 114 of diaphragm chamber 116 includes an inner sidewall 118.Upper shell 102 defines an upper half 120 of diaphragm chamber 116 andincludes an inner sidewall 122. As can be seen in FIG. 1B, diaphragm 106is pressed up against inner sidewall 122 of diaphragm chamber 116 in anextreme upper position. If the pressure of fluid traveling throughflow-through tube 108 increases, diaphragm 106 would not be able to moveany further upwardly and the pressure pod would not be able to generatea detectable corresponding gas pressure increase to signify the increasein fluid pressure.

Upper shell 102 defines a pressure port 124 through which gas on theupper side of diaphragm 106 can travel, for example, upwardly throughpressure port 124 and into a pressure line (not shown) that can be inoperable fluid communication with a pressure sensor (not shown). Asdiaphragm 106 moves downwardly, gas can be pulled into upper half 120 ofdiaphragm chamber 116 through pressure port 124 resulting in a pressuredecrease that can be detected by the pressure sensor. Changes in gaspressure of gas in pressure port 124, in the pressure line, and on theupper side of diaphragm 106, can be sensed by the pressure sensor andused to determine a pressure of fluid flowing through flow-through tube108.

FIG. 2 is a schematic, cross-sectional view of a pressure pod 200 thatis similar to pressure pod 100 shown in FIGS. 1A and 1B. In FIG. 2, adiaphragm 206 is shown in a mid-body position between a lower half 214and an upper half 220 of a diaphragm chamber 216. The upward pointingarrow denotes the direction of travel that diaphragm 206 can undergowhen exposed to increases in pressure of fluid flowing throughflow-through tube 208. The dashed line shown along an upper innersidewall 222 of diaphragm chamber 216 denotes an extreme upper positionthat diaphragm 206 can take under maximum detectable pressureconditions. The downward pointing arrow denotes the direction diaphragm206 can move when diaphragm 206 is exposed to negative or low-pressureconditions due to decreases in the pressure of fluid flowing throughflow-though tube 208. The dashed line at the bottom of diaphragm chamber216 denotes an extreme lower position that diaphragm 216 can take underminimum detectable pressure conditions.

FIG. 3 is a schematic illustration of a pressure pod diaphragm control,block diagram showing an exemplary system 300 comprising both anarterial side pressure pod 302 and a venous side pressure pod 304, andshowing system components for controlling both. As shown in FIG. 3, ablood circuit 306 includes a bloodline 308 that forms a fluidcommunication from a patient to an arterial side pressure pod 302 andfrom pressure pod 302 to a blood pump 310. Bloodline 308 then includes afluid communication from blood pump 310 to a dialyzer 312, and fromdialyzer 312 to venous side pressure pod 304. Bloodline 308 then returnsblood to a patient after it flows through pressure pod 304. Arterialside pressure pod 302 includes a diaphragm 314. Diaphragm 314 dividespressure pod 302 into a flow-through fluid half below diaphragm 314, anda gas half 316 that is in fluid communication with a pressure sensor318. Pressure sensor 318 senses gas pressure within gas half 316 ofpressure pod 302 and sends a signal representative of the gas pressureto a central processing unit (CPU) 320. Based on the signal receivedfrom pressure sensor 318, CPU 320 can determine whether or notadjustments are needed to the position of diaphragm 314. For example,when the pressure signal indicates that pressure within the gas half 316is within an acceptable range and pressure increases and decreases arebeing properly detected, CPU 320 can determine that no adjustments areneeded to the position of diaphragm 314. If, on the other hand, based onthe signal sent from pressure sensor 318, CPU 320 determines that moregas pressure is needed in gas half 316, CPU 320 sends a signal toactivate an air pump 322 that can force pressurized gas into gas half316 through a valve 324. Valve 324 can comprise, for example, a two-wayvalve as shown. Simultaneously, CPU 320 can send a signal to valve 324so that valve 324 is opened and pressurized gas generated by air pump322 can be forced into gas half 316. By controlling air pump 322 andvalve 324 based on signals received from pressure sensor 318, CPU 320can regulate the gas pressure in gas half 316 and thus maintaindiaphragm 314 in a mid-body position within pressure pod 302. Themid-body position enables diaphragm 314 to move upwardly or downwardlyas a result of pressure increases and decreases, respectively, in thesegment of bloodline 308 coming from the patient.

On the venous side of system 300, blood that has been pumped by bloodpump 310 along bloodline 308, and through dialyzer 312, passes throughvenous side pressure pod 304. Pressure increases and decreases,including pressure pulses, of blood passing through pressure pod 304,are detected by movement of a diaphragm 330 within pressure pod 304.Similar to the construction of pressure pod 302, pressure pod 304includes a gas half 332 defined as the volume above diaphragm 330.Pressure changes in the gas in gas half 332 are detected by a pressuresensor 334 that sends a signal to CPU 320. CPU 320 receives the pressuresignal from pressure sensor 334 and controls an air pump 336 and a valve338 to regulate the pressure within gas half 332. If the gas pressurewithin gas half 332 exceeds a maximum, threshold, and/or predeterminedvalue, CPU 320 can control valve 338 and air pump 336 such that gas fromgas half 332 can be vented through valve 338, through air pump 336, andout through a vent 340. Then, diaphragm 330 can assume a more mid-bodyposition within the diaphragm chamber of pressure pod 304. If the gaspressure with gas half 332 falls below a minimum, threshold, and/orpredetermined value, CPU 320 can control valve 338 and air pump 336 suchthat gas can be pumped by air pump 336 though valve 338 and into gashalf 332 so that diaphragm 330 can assume a more mid-body positionwithin the diaphragm chamber of pressure pod 304.

FIG. 4 is a process flow diagram showing the algorithm involved withautomatically controlling the position of a pressure pod diaphragm, inaccordance with the present teachings. The algorithm can be used forcontrolling each pressure pod of the system, for example, in a systemcomprising in arterial side pressure pod and a venous side pressure pod,each pressure pod can be controlled independently of the other. For thealgorithm shown in FIG. 4, control of a venous side pressure pod isexemplified. As shown in FIG. 4, once a dialysis treatment commences,gas pressure on the gas side of the venous pressure pod is detected by apressure sensor. A signal corresponding to the sensed pressure is sentto a CPU. As shown in step 400, pressure on the gas side of the venouspressure pod can be sensed by the pressure sensor and a correspondingsignal can be sent to the CPU every 50 milliseconds (msec). The CPU canthen average the pressure signals received every 50 msec to generateaverage venous pressure data in a step 402. Each new incoming pressuresignal received by the CPU is then compared to the average venouspressure data (the average value) and a determination is made in step404 as to whether the measured value deviates from the average value bymore than 5 mmHg. If the measured pressure does deviate from the averageby than 5 mmHg, then the CPU, in a step 406, can reset all the valuesand indicate that the pressure in the gas half of the venous pressurepod is changing. In response, a new set of pressure readings can betaken over a fresh interval of time and a new average venous pressuredata value can be generated. If, on the other hand, the pressuremeasured deviates from the average value by not more than 5 mmHg, thenthe CPU determines that the pressure is stable and, in a step 408, theCPU determines whether the pressure remains stable for 10 seconds,continuously. If the pressure does not remain stable for 10 secondscontinuously, such that a new measured pressured value does deviate fromthe average value by more than 5 mmHg, then the CPU makes adetermination that the venous side pressure pod diaphragm is correctlypositioned and no adjustments to the gas pressure in the gas half of thepressure pod are made. On the other hand, if the CPU determines that thepressure has remained stable for 10 seconds continuously, then the CPUdetermines, in a step 410, whether a vent command has been sent. If theCPU determines that a vent command has not been sent, then, in a step412, the CPU sends a vent venous pressure command, for example, toactivate a venting function for 20 msec, and steps 400, 402, and 404 arerepeated. A new pressure value is then sensed, and operation iscontinued. If the venting does not correct the positioning of thediaphragm and instead the pressure continues to remain stable, then, instep 410, the CPU determines whether 500 msec have elapsed since thevent command has been sent. If, in step 414, the CPU determines that 500msec have not elapsed, then the system continues to monitor the pressureat 50 msec intervals. If, in step 414, the CPU determines that 500 msechave elapsed since the vent command has been sent, then the CPAdetermines, in a step 416, whether a pump command has been sent. If apump command has not been sent, then in a step 418, the CPU sends avenous air pump command, for example, for 100 msec, and steps 400, 402,and 404 are repeated. If, in step 416, the CPU determines a pump commandhas been sent, then the CPU determines, in a step 420, whether 500 msechave elapsed since the pump command was sent. If, in step 420, it isdetermined that it has not been 500 msec since the pump command has beensent, then steps 400, 402, and 404 are repeated and the system continuesto monitor the pressure at 50 msec intervals. If 500 msec have elapsedsince the pump command has been sent, as determined in step 420, and thepressure continues to remain stable, then the CPU determines thediaphragm is stuck and the CPA enables a stuck alarm. The alarm can bean audible alarm, a flashing light, a combination thereof, or the like.

In addition, or as an alternative, the CPU can receive pressure signalsas, or translate pressure signals to, a waveform, and the waveform canbe analyzed by the CPU to determine whether pressure fluctuations areproperly being detected and to determine whether adjustments need to bemade to the gas pressure in the gas half of the pressure pod so as toadjust the position of the diaphragm. FIGS. 5A-5C show exemplarywaveforms with which the CPU can compare incoming pressure signalsshaped as waveforms. More particularly, FIGS. 5A-5C are three graphsshowing waveforms representing pressure signals generated by an arterialside pressure pod, over time, including a graph that corresponds topressure measurements taken under normal, proper operating conditions(FIG. 5A), a graph that corresponds to pressure measurements taken underconditions wherein the pressure pod diaphragm is stuck in a first,extreme, over-pressurized position (FIG. 5B), and a graph thatcorresponds to pressure measurements taken under conditions wherein thepressure pod diaphragm is stuck in a second, extreme, under-pressurizedposition (FIG. 5C). By comparing a waveform generated in real-time tovarious stored waveforms, such as those shown in FIGS. 5A-5C, the CPUcan determine whether the waveform generated in real-time, showssufficient fluctuations in pressure, over time, to conclude that thepressure pod diaphragm is properly positioned. By making such acomparison, the CPU can also determine whether the waveform is sosubstantially linear and non-fluctuating that the pressure pod diaphragmmust be stuck and not properly positioned, in which case correctiveaction can be taken or an alarm can be activated.

The entire contents of all references cited in this disclosure areincorporated herein in their entireties, by reference. Further, when anamount, concentration, or other value or parameter is given as either arange, preferred range, or a list of upper preferable values and lowerpreferable values, this is to be understood as specifically disclosingall ranges formed from any pair of any upper range limit or preferredvalue and any lower range limit or preferred value, regardless ofwhether such a range is separately disclosed. Where a range of numericalvalues is recited herein, unless otherwise stated, the range is intendedto include the endpoints thereof, and all integers and fractions withinthe range. It is not intended that the scope of the invention be limitedto the specific values recited when defining a range.

All patents, patent applications, and publications mentioned herein areincorporated herein in their entireties, by reference, unless indicatedotherwise.

Other embodiments of the present invention will be apparent to thoseskilled in the art from consideration of the present specification andpractice of the present invention disclosed herein. It is intended thatthe present specification and examples be considered as exemplary onlywith a true scope and spirit of the invention being indicated by thefollowing claims and equivalents thereof.

What is claimed is:
 1. A system for controlling the position of adiaphragm in a diaphragm-containing pressure pod, the system comprising;a fluid pump: a pressure pod comprising an interior defining aflow-through fluid side and a gas side, the flow-through fluid side andthe gas side being separated from one another by a diaphragm; a fluidconduit in fluid communication with the flow-through fluid side andoperatively positioned with respect to the fluid pump such that the pumpcan move fluid through the conduit and force fluid through theflow-through fluid side of the pressure pod; a pressure sensoroperatively connected to the gas side of the pressure pod and configuredfor sensing pressure resulting from movement of the diaphragm; a gassource in fluid communication with the gas side of the pressure pod andcomprising a valve configured to provide fluid communication between thegas side and the gas source, the valve also being configured tointerrupt communication between the gas side and the gas source; and acontroller configured to (1) receive a pressure signal generated by thepressure sensor, (2) compare the pressure signal received to apredetermined pressure signal that corresponds to a signal generatedduring normal operation of the pressure pod, under normal operatingpressures and where the diaphragm is properly or optimally positioned,(3) calculate a difference between the pressure signal received from thepressure sensor and the predetermined pressure signal, and (4) controlthe valve in response to the calculated difference, wherein the controlof the valve controls pressure in the gas side of the pressure pod,which in-turn controls the position of the diaphragm.
 2. The system ofclaim 1, wherein the controller is further configured such that, aftercontrolling the valve and in-turn controlling the position of thediaphragm to make an adjustment, the controller immediately compares anew pressure signal resulting from the adjustment, to one or morepredetermined signals.
 3. The system of claim 1, wherein the controllercomprises an oscilloscope, is configured to display pressure signals itreceives from the pressure sensor as a waveform on the oscilloscope, andis configured to compare the waveform to one or more predeterminedwaveforms.
 4. The system of claim 3, wherein the controller comprises amemory, the one or more predetermined waveforms are stored in thememory, and the one or more predetermined waveforms include a firstwaveform corresponding to a signal received when the diaphragm is in afirst extreme position, and a second waveform corresponding to a signalreceived when the diaphragm is in a second extreme position opposite thefirst extreme position.
 5. The system of claim 4, wherein the firstextreme position of the diaphragm is a position wherein the flow-throughfluid side of the pressure pod has a maximum volume and the gas side ofthe pressure pod has a minimum volume, and the second extreme positionof the diaphragm is a position wherein the volume of the flow-throughfluid side of the pressure pod is minimized and the volume of the gasside of the pressure pod is maximized.
 6. The system of claim 1, whereinthe controller is configured to compare a pressure signal received fromthe pressure sensor to a predetermined pressure signal corresponding tonormal operation of the pressure pod, and the controller is configuredto determine whether the pressure signal received is within anacceptable degree of variance relative to the predetermined pressuresignal.
 7. The system of claim 1, wherein the fluid pump comprises aperistaltic pump and the pressure sensor is configured for sensingpulses of pressure caused by the peristaltic pump moving fluid throughthe flow-through fluid side.
 8. The system of claim 1, wherein the valveis configured to move between an open position and a closed position,and the valve is configured in the open position to provide a gaseouscommunication between the gas side and an ambient atmosphere while fluidis being moved through the flow-through fluid side.
 9. The system ofclaim 1, further comprising a fluid within the conduit, wherein thefluid comprises blood and the gas source comprises pressurized gas undera pressure of greater than 1 atmosphere.
 10. A method for automaticallyadjusting the position of a diaphragm in a pressure pod, the methodcomprising; forcing a fluid a through a flow-through fluid side of apressure pod, using a pump, the pressure pod comprising a diaphragm, theflow-through fluid side being disposed on one side of the diaphragm, anda gas side being disposed on a side of the diaphragm opposite theflow-through fluid side; generating a pressure signal corresponding tothe pressure of fluid flowing through the flow-through fluid side of thepressure pod, over time; comparing the pressure signal to one orpredetermined pressure signals that correspond to a signal generatedduring normal operation of the pressure pod, under normal operatingpressures and where the diaphragm is properly or optimally positioned;and (i) releasing pressure from the gas side of the pressure pod, (ii)pressurizing the gas side of the pressure pod, or both (i) and (ii),based on the comparison, wherein the releasing pressure, thepressurizing, or both, are used to properly position the diaphragmbetween the flow-through fluid side and the gas side of the pressurepod.
 11. The method of claim 10, wherein the comparing comprisescomparing the pressure signal to a plurality of predetermined pressuresignals.
 12. The method of claim 10, wherein the releasing pressure,pressurizing, or both, comprises actuating a valve that is in fluidcommunication with the gas side of the pressure pod, to maintain thediaphragm in a mid-body position in the pressure pod.
 13. The method ofclaim 10, wherein the releasing pressure, pressurizing, or both,comprises pressurizing the gas side of the pressure pod, and thepressurizing comprises opening a valve to form a fluid communicationbetween the gas side of the pressure pod and a pressurized gas source sothat pressurized gas from the pressurized gas source enters the gas sideof the pressure pod, to maintain the diaphragm in a mid-body position inthe pressure pod.
 14. The method of claim 10, wherein the releasingpressure, pressurizing, or both, comprises releasing pressure from thegas side of the pressure pod, and the releasing pressure comprisesopening a valve to form a fluid communication between the gas side ofthe pressure pod and an ambient atmosphere, the opening causingpressurized gas in the gas side of the pressure pod to vent gas from thegas side to the ambient atmosphere, to maintain the diaphragm in amid-body position in the pressure pod.
 15. The method of claim 10,wherein the pump comprises a peristaltic pump and the pressure signalcomprises pressure pulses resulting from the peristaltic pump moving thefluid through the flow-through fluid side of the pressure pod.
 16. Themethod of claim 10, wherein the comparing comprises comparing thepressure signal to one or more predetermined pressure signals.
 17. Themethod of claim 10, wherein the comparing comprises comparing thepressure signal to one or more predetermined waveforms.
 18. The methodof claim 10, wherein the comparing comprises calculating an averagedeviation of the generated pressure signal relative to a predeterminedsignal, and determining whether the calculated average deviation iswithin an acceptable range of deviation.
 19. The method of claim 10,wherein the releasing, pressurizing, or both, comprises: venting gasfrom the gas side of the pressure pod; generating a new pressure signal,after the venting, corresponding to the pressure of fluid flowingthrough the flow-through fluid side of the pressure pod; determiningthat the new pressure signal does not substantially deviate from anaverage pressure signal; pressurizing the gas side of the pressure podafter generating the new pressure signal; and generating yet anotherpressure signal, all while fluid is being moved through the flow-throughfluid side.
 20. The method of claim 19, wherein the determining that thenew pressure signal does not substantially deviate from the averagepressure signal comprises determining whether the new pressure signalcorresponds to a pressure that is at least 5 mmHg higher or lower thanthe average pressure signal.
 21. The method of claim 10, wherein thereleasing, pressurizing, or both, results in an adjustment of theposition of the diaphragm and a new pressure signal, and the methodfurther comprises, after the releasing, pressurizing, or both,immediately comparing the new pressure signal to one or morepredetermined signals.